Fig. 1. Design of metasurface structure. (a) Schematic diagram of BIC metasurface structure array; (b) schematic diagram of geometric parameters of unit cell

Fig. 2. Transmission spectra and mode analysis results of structure under x-polarized wave incidence. (a) Transmission spectra of structures with different l₁; (b) transmission spectrum of structure with l₁=90 μm; multipole scattering power distributions of (c) mode I and (d) mode II with electric field distribution of resonance mode shown in inset; (e) resonance frequency of quasi-BIC mode versus l₁; (f) Q-factor of quasi-BIC mode versus asymmetric parameter α

Fig. 3. Transmission spectra and mode analysis results of structure under y-polarized wave incidence. (a) Transmission spectra of structures with different l₁; (b) transmission spectrum of structure with l₁=90 μm; (c) multipole scattering power distribution of mode III with electric field distribution of resonance mode shown in inset; (d) resonance frequency of quasi-BIC mode versus l₁; (e) Q-factor of quasi-BIC mode versus asymmetric parameter α

Fig. 4. Fabricated sensors and test system. (a) Image of fabricated sensor and microscopic images with different parameters;

Fig. 5. Spectra under different l₁ with BIC shown by pentagram. (a) Simulated result under x-polarized wave incidence; (b) measured result under x-polarized wave incidence; (c) simulated result under y-polarized wave incidence; (d) measured result under y-polarized wave incidence

Fig. 6. Refractive index sensing characteristic. (a) Transmitted spectra under different analyte refractive indexes; (d) resonance frequency versus refractive index of analyte

Fig. 7. Results of antibiotic sensing study on BIC metasurface. (a) Transmission spectra under different analyte mass concentrations; (b) magnified view of resonance valleys; (c) resonance frequency and intensity of transmission spectrum versus analyte mass concentration; (d) frequency and (e) amplitude of resonant valley of measured spectrum after each cleaning